Melamine derivatives as flame retardants for polyurethanes

ABSTRACT

Flame retarded polyurethane foams are prepared from a reaction mixture comprising as the flame retardant additive the compound N,N&#39;-bis(1-hydroxy-2,2,2-trichloroethyl)melamine or its derivatives.

BACKGROUND OF THE INVENTION

This invention relates to a flame retarded polyurethane foam, and moreparticularly, a polyurethane foam prepared by adding to the reactionmixture a derivative compound of melamine containing the2,2,2-trichloroethyl group.

Prior to the instant invention, polyurethane foam was made flameretarded normally by incorporating phosphorus and/or halogen containingcompounds into the polyurethane formulation. One such flame retardantfor polyurethane foam is 2,3-dibromo-2-butene-1, 4-diol which isdescribed in U.S. Pat. Nos. 3,919,166 and 4,022,718. The disadvantagesof this material are its relatively high cost and its poorprocessibility at high loadings. U.S. application Ser. No. 890,358discloses N,N'-di(1-hydroxy-2,2,2-trichloroethyl) urea as a flameretardant additive for polyurethane foam. Although this compound is aneffective flame retardant, it is soluble in the polyols used forpreparing the polyurethane foam and thus decrease the load bearingproperties of the foam.

The compounds of the present invention overcome the disadvantages of theprior art because they are insoluble in the polyol and thus increase theload bearing properties of flexible polyurethane foams as measured bythe Indentation Load Deflection test described in ASTM D 2406-73. (TheIndentation Load Deflection test is a measure of the force necessary toindent a foam sample to a specified thickness). The compounds of thisinvention also do not adversely affect the support (sag) factor of thefoam as do prior art compounds. The support (sag) factor is measured asthe ratio of the 65% Indentation Load Deflection value to the 25%Indentation Load Deflection value and is related to foam comfort.

STATEMENT OF THE INVENTION

The present invention is directed to a flame retarded polyurethane foamprepared from a reaction mixture which comprises a flame retardingamount of a compound having the formula ##STR1## 10 wherein: (a) R isselected from ##STR2## (b) R¹ is selected from H or R; (c) R² isselected from an alkyl of 1 to 5 carbons, or ##STR3## (d) R³ is selectedfrom H, CH₃, CCl₃, CH₂ CCl₃ ; and

(e) x is an integer from 1-10.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a flame retarded polyurethane foam.The most common types of polyurethanes are formed by the reaction oftoluene diisocyanate (TDI) or polymethylene polyphenylisocyanate ormixtures thereof, with polyfunctional hydroxy compounds. The flameretardant additives described in this invention are effective as flameretardants for hot-cure flexible polyurethane foam, high-resiliency (HR)polyurethane foam, rigid polyurethane foam, and rigidpolyurethane/isocyanurate foam copolymers.

The flame retardant additives used to prepare the polyurethane foams ofthis invention may be prepared by the reaction of melamine with chloralor chloral hydrate following the method of Bump and Atkinson, Journal ofthe American Chem. Soc., Volume 72, page 629, (1950). The melamine isstirred with chloral or chloral hydrate in a solvent at 25° to 150° C.,preferably 70° to 90° C., to afford the desired composition. Solventsthat may be used in these reactions include water, ether, benzene,toluene and tetrahydrofuran. Catalysts that may be used to increase therate of reaction between chloral and the nitrogen-containing compoundinclude hydrochloric acid, sulfuric acid, acetic acid or borontrifuoride etherate.

These compounds are added to the reactants for preparing thepolyurethane foams in the amount of 0.25 to 30 parts per 100 parts ofthe polyol (php) component by weight to impart flame retardancy. Thepreferred loading in high-resiliency polyurethane foam is 0.5 to 2.0 phpby weight.

Representative flame retardant additives used in this invention are:##STR4##

The preferred additives for use as flame retardants in polyurethane foamare: ##STR5##

The flame retardant additives used in this invention may also be furtherreacted with various unsubstituted or halogen substituted epoxides toincrease the molecular weight of the flame retardant and/or increase thehalogen content. Epoxides useful for these purposes include ethyleneoxide, propylene oxide, 3,3,3-trichloro-1, 2-propylene oxide, and4,4,4-trichloro-1, 2-butylene oxide. Representative products of thisreaction are: ##STR6## where R³ =H, CH₃, CCl₃, or CH₂ --CCl₃ where m andn are integers with values of 1-10.

The following examples illustrate the present invention but are notintended to limit the invention thereto.

Polyurethane foams described in the following examples are made bydissolving the flame retardant additive in the polyol followed byaddition of catalysts, surfactant, water and/or blowing agent andisocyanate as described by K. C. Frisch and S. L. Reegan in "Advances inUrethane Science and Technology", Vol. 1-4, Technomic Publishing Co.Conn., 1971-1976. In the case of flexible foams, this mixture is stirredby a high-speed mixer and is poured into a 13×13×5-inch mold which mayor may not be clamped shut. After the reaction is completed, the foam isremoved and aged at room temperature for at least seven days(conventional hot-cure foams are cured at 110° C. for 1/2 hour prior toaging). Rigid foams are made by pouring the stirred reaction mixtureinto an 8×8×5-inch box and allowing the reaction to proceed under "freerise" conditions. The physical properties of the flexible foams are thenevaluated using ASTM D-2406-73; the flame retardant properties of bothflexible and rigid foams are evaluated using ASTM D-1692-74 and/or ASTMD-2863-74 or MVSS-302.

EXAMPLE 1 Preparation of N,N'-bis(1-hydroxy-2,2,2-trichloroethyl)melamine

This compound has previously been prepared by Bump and Atkinson [J. AmChem. Soc., 72, 629 (1950)]. Melamine (44.2 g, 0.3 mole) was added allat once to a stirred solution of chloral (221.2 g, 1.5 mole) dissolvedin 375 ml. of water at 70°-80° C. The reaction mixture was stirred for 3hours and the white precipitated product was filtered to give an 81%yield after drying. The product had a melting point >200° C. anddecomposed on further heating.

The infrared spectrum and elemental analysis of the compound wereconsistent with the assigned structure: ##STR7##

Anal. Calcd.: C, 20.0; H, 1.90; N, 20.0; Cl, 50.6 Found: C, 20.0; H,2.04; N, 19.8; Cl, 49.1

EXAMPLE 2 Preparation of N,N'-bis(1,2,2,2-tetrachloroethyl) melamine

This compound has previously been prepared by Dolatyan and Kostanyan[Arm. Khim. Zh., 20, 123 (1967)]. A mixture of phosphorus pentachloride(43.8 g, 0.1 mole) and the composition of Example 1 (42.1 g, 0.1 mole)were stirred in 100 ml. ether at room temperature overnight. Thereaction mixture was filtered and the filtrate was evaporated to givethe crude product. The product was washed with hexane, filtered anddried to afford 25 g (56%) of material having a m.p. of 245° C. (Lit.250°-2° C.).

The infrared spectrum of the compound was consistent with the assignedstructure: ##STR8##

EXAMPLES 3--5

The compound synthesized in Example 1 was incorporated into thefollowing high-resiliency polyurethane formulation:

    ______________________________________                                                              Parts                                                   ______________________________________                                        Pluracol 538 (BASF Wyandotte).sup.1                                                                   60                                                    Pluracol 581 (BASF Wyandotte).sup.2                                                                   40                                                    H.sub.2 O               2.7                                                   Dabco 33LV (Air Products).sup.3                                                                       0.3                                                   Niax A-1 (Union Carbide).sup.4                                                                        0.12                                                  Niax A-4 (Union Carbide).sup.5                                                                        0.3                                                   T-12 (M&T).sup.6        0.03                                                  DCF-1630 (Dow Corning).sup.7                                                                          0.04                                                  Niax SF-58 (Union Carbide).sup.8                                                                      34.9                                                  Additive                see Table 1                                           ______________________________________                                         .sup.1 Polyether polyol containing primary OH groups, OH number = 35          .sup.2 Polymer polyol                                                         .sup.3 33% Triethylene diamine, 67% Dipropylene glycol                        .sup.4 70% Bis(dimethylaminoethyl)ether, 30% Diluent                          .sup.5 33% Dimethylamino dimethylpropionamide, 67% Diluent                    .sup.6 Dibutyltin dilaurate                                                   .sup.7 Silicone surfactant                                                    .sup.8 80% (80/20 mixture of 2.4/2.6 toluene diisocyanate), 20% polymeric     isocyanate                                                               

                  Table 1                                                         ______________________________________                                                                                  MVSS-                                                    ILD    (lb/50 Support                                                                              302                                 Ex.                  Values.sup.1                                                                         in).sup.2                                                                            (Sag)  Flamm.                              #    php    Additive 25%    65%    Factor.sup.2                                                                         Test                                ______________________________________                                        3    --     None     39       99   2.5    Burns-                                                                        rate less                                                                     than 2                                                                        in/min                              4    3      Example  45        113 2.5    Self ex-                                        1                             tinguish-                                       Com-                          ing - does                                      pound                         not con-                                                                      tinue to                                                                      burn                                5    3      Fyrol    42       95   2.3    Self ex-                                        CEF                           tinguish-                                       [Tris (2-                     ing - does                                      chloro-                       not con-                                        ethyl)                        tinue to                                        phos-                         burn                                            phate]                                                            ______________________________________                                         .sup.1 Indent Load Deflection Test  ASTM D 240673                             .sup.2 Ratio of 65% ILD to 25% ILD                                       

The results of the 25% and 65% Indent Load Deflection tests (ASTMD-2406-73) on the compound of Example 1 (Example 4) are higher than thecontrol foam without flame retardant (Example 3) and the foam with tris(2-chloroethyl) phosphate (Example 5). In addition, the support factor(65% ILD/25% ILD) for the foam containing the compound of Example 1(Example 4) is comparable to the control (Example 3) whereas it islarger than the foam containing tris (2-chloroethyl) phosphate (Example5).

EXAMPLES 6-7

    ______________________________________                                        Formulation (flexible polyurethane foam)                                                             Parts                                                  ______________________________________                                        Polyol Poly G 30-56 (Olin).sup.1                                                                       100.0                                                Water                    3.5                                                  Surfactant L5710 (Union Carbide).sup.2                                                                 1.0                                                  Catalyst T-9 (M & T).sup.3                                                                             0.2                                                  Catalyst Dalco 33 LV (Air Products).sup.4                                                              0.3                                                  Isocyanate - TDI (Olin).sup.5                                                                          45.0                                                 Additive                 See Table 2                                          ______________________________________                                    

                  Table 2                                                         ______________________________________                                                          Flame Data                                                                              ASTM D-1692                                       Ex. #   Additive    php     (inches burned)                                                                         LOI                                     ______________________________________                                        6       none        --      Total     17.4                                    7       Compound of 9       2.7       19.5                                            Example #1                                                            ______________________________________                                         .sup.1 Polyether polyol, molecular weight >3,000, OH number = 56              .sup.2 Silicon surfactant                                                     .sup.3 Stannous octoate                                                       .sup.4 33% Triethylenediamine, diamine, 67% Dipropylene glycol                .sup.5 80/20 mixture of 2,4/2,1 toluene diisocyanate                     

EXAMPLES 8-9

    ______________________________________                                        Formulation (rigid polyurethane foam)                                                                Parts                                                  ______________________________________                                        Polyol Poly G71-530 (Olin).sup.1                                                                       100.0                                                Surfactant DC-193 (Dow).sup.2                                                                          1.5                                                  Dimethylaminoethanol     2.94                                                 Dibutyltin dilaurate     0.06                                                 Blowing Agent Isotron 11 (Pennwalt).sup.3                                                              30.0                                                 Isocyanate - PAPI (Upjohn).sup.4                                                                       See Table 3                                          Additive                 See Table 3                                          ______________________________________                                    

                  Table 3                                                         ______________________________________                                                          Flame Data                                                                              ASTM D 1692                                       Ex. #   Additive    php     (inches burned)                                                                          LOI                                    ______________________________________                                        8       Compound of  25     1.6        21.6                                           Example 1                                                                     PAPI        173                                                       9       none        --                                                                PAPI        145     5.0        20.8                                   ______________________________________                                         .sup.1 Polyether polyol, OH number = 530, functionality = 4.5                 .sup.2 Silicone surfactant                                                    .sup.3 Fluorocarbon 11 (CCl.sub.3 F)                                          .sup.4 Polymeric isocyanate, NCO equivalent = 133                        

EXAMPLE 10

To the rigid-foam formulation of Examples 8-9 was added 30 pph of thecomposition of Example 2. The foam was self extinguishing and gaveflammability results equivalent to that of Example 8.

EXAMPLE 11

One mole of the composition of Example 1 was reacted with 2.2 moles ofpropylene oxide at 50°-100° C. in the presence of 1.0 g of BF₃ etheratecatalyst to give a compound consistent with the assigned structure:##STR9##

EXAMPLE 12

To the rigid foam formulation of Examples 8-9 was added 30 pph of thecomposition of Example 11. The foam was self extinguishing and gaveflammability results equivalent to that of Example 8.

What is claimed:
 1. A polyurethane foam prepared from a reaction mixturewhich comprises a flame retarding amount of a compound having theformula ##STR10## wherein: (a) R is selected from ##STR11## (b) R¹ isselected from H or R; (c) R² is selected from an alkyl of 1 to 5carbons, or ##STR12## (d) R³ is selected from H, CH₃, CCl₃, CH₂ CCl₃ ;and(e) x is an integer from 1-10.
 2. The polyurethane foam of claim 1wherein the compound is ##STR13##
 3. The polyurethane foam of claim 1wherein the compound is ##STR14##
 4. The polyurethane foam of claim 1wherein the polyurethane foam is rigid foam.
 5. The polyurethane foam ofclaim 1 wherein the polyurethane foam is high-resiliency foam.
 6. Thepolyurethane foam of claim 1 wherein the polyurethane foam is flexiblefoam.
 7. The polyurethane foam of claim 1 wherein the compound is##STR15##